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Assessing the unconscious patient

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ABCDE

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Causes of impaired consciousness

  • Sagittal sinus thrombosis
  • Subarachnoid haemorrhage
  • Thalamic haemorrhage
  • Pontine haemorrhage
  • Subdural haemorrhage
  • Intracerebral bleed
  • Massive supratentorial infarction
  • Brainstem infarction
  • Brainstem haemorrhage
  • Brainstem thrombencephalitis
  • Trauma: contusion, concussion
  • Hydrocephalus
  • Midline brainstem tumour
  • Unilateral hemispheric mass with herniation
  • Cerebral abscess
  • Subdural empyema
  • Thrombophlebitis
  • Bacterial meningitis
  • Viral encephalitis
  • Postinfectious encephalomyelitis
  • Syphilis
  • Amphetamines
  • Lithium
  • Phencyclidine
  • Monoamine oxidase inhibitors
  • Hypoxia
  • Hypercapnia
  • Hypernatremia
  • Hypoglycemia
  • Hyperglycemic nonketotic coma
  • Diabetic ketoacidosis
  • Lactic acidosis
  • Hypercalcemia
  • Hypocalcemia
  • Hypermagnesemia
  • Hyperthermia
  • Hypothermia
  • Reye syndrome
  • Aminoacidemia
  • Wernicke encephalopathy
  • Porphyria
  • Hepatic encephalopathy
  • Uremia
  • Sepsis
  • Typhoid fever
  • Malaria
  • Creutzfeldt-Jakob disease
  • Lead
  • Thallium
  • Mushrooms
  • Cyanide
  • Methanol
  • Ethylene glycol
  • Carbon monoxide
  • Sedatives
  • Barbiturates
  • Other hypnotics
  • Tranquilizers
  • Bromides
  • Alcohol
  • Opiates
  • Paraldehyde
  • Salicylate
  • Psychotropics
  • Anticholinergics
  • Dialysis encephalopathy
  • Addisonian crisis
  • Pituitary apoplexy
  • Hypothyroidism
  • Waterhouse-Friderichsen syndrome
  • Seizure
  • Nonconvulsive status epilepticus
  • Central pontine myelinolysis
  • Thrombotic thrombocytopenic purpura
  • Disseminated intravascular coagulation
  • Nonbacterial thrombotic endocarditis
  • Subacute bacterial endocarditis
  • Multifocal leukoencephalopathy
  • Adrenal leukodystrophy
  • Cerebral vasculitis
  • Multiple sclerosis
  • Leukoencephalopathy associated with chemotherapy
  • Fat emboli
  • Delirium
  • Catatonia

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History

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History: still nearly always the most useful tool

  • Witnesses
  • Friends / family
  • Paramedics
  • Personal effects
  • Old ED records
  • WCP
  • Old notes

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Questions to ask

  • Time course?
    • Abrupt / gradual / fluctuating
  • Focal signs / symptoms before?
    • Hemiparesis? Headache? Vomiting? Visual symptoms?
  • Previous similar episodes?
    • Perhaps seizure?
  • Other recent symptoms?
    • Fever? Increasing headache? Falls? Delirium?
  • Medications?
  • Alcohol / drug abuse?

?

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Examination

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Examination

  • Still plenty of clues to find even if the patient can’t co-operate

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Vital signs

  • Hypertension?
    • Intracranial haemorrhage / hypertensive encephalopathy / transtentorial herniation
  • Hypotension?
    • Hypovolaemic / sepsis / cardiogenic shock / drugs / adrenal crisis
  • Hyperthermia?
    • Infection / anticholinergics/ serotonin syndrome / heat stroke
  • Hypothermia
    • Environmental / sepsis / drugs or alcohol / adrenal crisis
  • Respiratory rate?
    • CO2 narcosis / opiates

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Observation

Sign

Could suggest

Bruising

Trauma, corticosteroid use, anticoagulants, liver disease

Rash

Infection (meningococcal?), vasculitis, fat emboli

Jaundice

Liver disease

Cherry-red skin / lips

CO poisoning

Cyanosis

Hypoxaemia ± CO2 retention

Needle marks

Drug abuse

Hyper-pigmentation

Addison’s Disease, porphyria

Splinter haemorrhages

Subacute bacterial endocarditis, sepsis

Trauma

Traumatic brain injury, seizures

Neck stiffness

Meningitis

James Heilman, MD [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

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Neurological examination in an unconscious patient 1

  • Level of consciousness
    • GCS
  • Muscle tone and reflexes
    • Looking for obvious asymmetry
    • Decreased tone or reflexes on one side suggest an acute structural brain problem

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Neurological examination in an unconscious patient 2

  • Pupils
    • Small: opiates, organophosphates, nerve agents, pontine lesions
    • Large: TCAs, antihistamines, SSRIs, raised ICP
    • Asymmetry: Raised ICP (but small differences can be normal)
  • Eye position
    • Conjugate deviation to one side suggests large cerebral lesion or seizures

Image 1: Nutschig at the English language Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)]

Image 2: Public domain

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Investigations

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Blood tests for an unconscious patient from unknown cause

In most patients

  • FBC
  • U&E
  • Ca2+/Mg2+
  • Glucose
  • LFT
  • Lactate
  • Osmolality
  • ABG
  • Drug screen (particularly aspirin and paracetamol)

In selected patients

  • Adrenal function tests
  • Thyroid function test
  • Blood cultures
  • CO
  • Specific serum drug concentrations

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Neuroimaging

  • CT is the best first test
    • Accessible and fast
  • Sensitive for
    • Haemorrhage
    • Hydrocephalus
    • Tumours
    • Large strokes

​

  • Less sensitive for
    • HSV encephalitis
    • Early strokes
    • Diffuse axonal injury
    • Hypoxic brain injury

Image: daveynin from United States - New UPMC East Uploaded by crazypaco, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=20326407

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By Lucien Monfils - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=51153636

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© Ian W Turnbull

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Lumbar puncture

  • For patients with suspected CNS infection or with suspected SAH despite normal CT
  • Low GCS requires CT before LP
  • If strong suspicion of CNS infection treat pending LP (but please at least do some blood cultures first!)

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EEG

  • Purpose in acute coma is to diagnose non-convulsive status epilepticus
  • Consider if subtle signs of seizure (e.g. rhythmic synchronous muscle movements or nystagmus) or no diagnosis despite other investigations

Image: Der Lange [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0/)]

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The end

https://acutemedwales.org.uk/unconscious-patient/